This invention relates to hydraulic cements containing epoxide resins. More particularly, this invention relates to pre-formed or pre-cast concrete articles which have been modified with thermosetting epoxide resin compositions.
The modification of hydraulic cements with epoxide resins is well known. See, for example, U.S. Pat. Nos. 3,477,979, 3,310,511, 3,198,758, and 3,240,736.
However, the use of epoxide resins in preparing pre-cast concrete articles has been difficult for several reasons. In the first place, the prior art employed essentially liquid or resinous epoxide resins and room temperature curing agents. Thus, the pot life or working life of the composition was severely limited, as the mixture immediately begins setting up when the epoxide resin curing agent and the liquid epoxy resin are mixed together. In addition, the use of two-component systems necessarily means that errors in mixing on the job site often occur. Finally, because of the room temperature curable properties of the curing agent/epoxy resin mixture, large amounts of waste occur due to premature curing.
Another significant problem in utilizing liquid epoxy resins in combination with hydraulic cement has been the difficulty in obtaining a uniform composition dispersion in the reaction mixture. Furthermore, as the mixture is worked to insure uniform distribution throughout the mold, the liquid epoxide resin often migrates to the surface, significantly reducing pot life and cured state properties.
Thus, it is an object of this invention to provide a one-package hydraulic cement-based system.
It is another object of this invention to provide epoxide resin-containing cements having improved workability and indefinite pot lives.
It is yet another object of this invention to prepare a pre-cast concrete object which possessess improved strength, adhesion and chemical resistance properties.
These and other objectives are obtained by preparing the compositions of the instant invention.